sysdeps/i386/nptl/tls.h

   1 /* Definition for thread-local data handling.  nptl/i386 version.
   2    Copyright (C) 2002-2018 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _TLS_H
  20 #define _TLS_H  1
  21
  22 #include <dl-sysdep.h>
  23 #ifndef __ASSEMBLER__
  24 # include <stdbool.h>
  25 # include <stddef.h>
  26 # include <stdint.h>
  27 # include <stdlib.h>
  28 # include <sysdep.h>
  29 # include <libc-pointer-arith.h> /* For cast_to_integer. */
  30 # include <kernel-features.h>
  31 # include <dl-dtv.h>
  32
  33 typedef struct
  34 {
  35   void *tcb;            /* Pointer to the TCB.  Not necessarily the
  36                            thread descriptor used by libpthread.  */
  37   dtv_t *dtv;
  38   void *self;           /* Pointer to the thread descriptor.  */
  39   int multiple_threads;
  40   uintptr_t sysinfo;
  41   uintptr_t stack_guard;
  42   uintptr_t pointer_guard;
  43   int gscope_flag;
  44   /* Bit 0: X86_FEATURE_1_IBT.
  45      Bit 1: X86_FEATURE_1_SHSTK.
  46    */
  47   unsigned int feature_1;
  48   /* Reservation of some values for the TM ABI.  */
  49   void *__private_tm[3];
  50   /* GCC split stack support.  */
  51   void *__private_ss;
  52   void *__glibc_reserved2;
  53 } tcbhead_t;
  54
  55 /* morestack.S in libgcc uses offset 0x30 to access __private_ss,   */
  56 _Static_assert (offsetof (tcbhead_t, __private_ss) == 0x30,
  57                 "offset of __private_ss != 0x30");
  58
  59 # define TLS_MULTIPLE_THREADS_IN_TCB 1
  60
  61 #else /* __ASSEMBLER__ */
  62 # include <tcb-offsets.h>
  63 #endif
  64
  65
  66 /* Alignment requirement for the stack.  For IA-32 this is governed by
  67    the SSE memory functions.  */
  68 #define STACK_ALIGN     16
  69
  70 #ifndef __ASSEMBLER__
  71 /* Get system call information.  */
  72 # include <sysdep.h>
  73
  74 /* The old way: using LDT.  */
  75
  76 /* Structure passed to `modify_ldt', 'set_thread_area', and 'clone' calls.  */
  77 struct user_desc
  78 {
  79   unsigned int entry_number;
  80   unsigned long int base_addr;
  81   unsigned int limit;
  82   unsigned int seg_32bit:1;
  83   unsigned int contents:2;
  84   unsigned int read_exec_only:1;
  85   unsigned int limit_in_pages:1;
  86   unsigned int seg_not_present:1;
  87   unsigned int useable:1;
  88   unsigned int empty:25;
  89 };
  90
  91 /* Initializing bit fields is slow.  We speed it up by using a union.  */
  92 union user_desc_init
  93 {
  94   struct user_desc desc;
  95   unsigned int vals[4];
  96 };
  97
  98
  99 /* This is the size of the initial TCB.  Can't be just sizeof (tcbhead_t),
 100    because NPTL getpid, __libc_alloca_cutoff etc. need (almost) the whole
 101    struct pthread even when not linked with -lpthread.  */
 102 # define TLS_INIT_TCB_SIZE sizeof (struct pthread)
 103
 104 /* Alignment requirements for the initial TCB.  */
 105 # define TLS_INIT_TCB_ALIGN __alignof__ (struct pthread)
 106
 107 /* This is the size of the TCB.  */
 108 # define TLS_TCB_SIZE sizeof (struct pthread)
 109
 110 /* Alignment requirements for the TCB.  */
 111 # define TLS_TCB_ALIGN __alignof__ (struct pthread)
 112
 113 /* The TCB can have any size and the memory following the address the
 114    thread pointer points to is unspecified.  Allocate the TCB there.  */
 115 # define TLS_TCB_AT_TP  1
 116 # define TLS_DTV_AT_TP  0
 117
 118 /* Get the thread descriptor definition.  */
 119 # include <nptl/descr.h>
 120
 121
 122 /* Install the dtv pointer.  The pointer passed is to the element with
 123    index -1 which contain the length.  */
 124 # define INSTALL_DTV(descr, dtvp) \
 125   ((tcbhead_t *) (descr))->dtv = (dtvp) + 1
 126
 127 /* Install new dtv for current thread.  */
 128 # define INSTALL_NEW_DTV(dtvp) \
 129   ({ struct pthread *__pd;                                                    \
 130      THREAD_SETMEM (__pd, header.dtv, (dtvp)); })
 131
 132 /* Return dtv of given thread descriptor.  */
 133 # define GET_DTV(descr) \
 134   (((tcbhead_t *) (descr))->dtv)
 135
 136 /* Macros to load from and store into segment registers.  */
 137 # ifndef TLS_GET_GS
 138 #  define TLS_GET_GS() \
 139   ({ int __seg; __asm ("movw %%gs, %w0" : "=q" (__seg)); __seg & 0xffff; })
 140 # endif
 141 # ifndef TLS_SET_GS
 142 #  define TLS_SET_GS(val) \
 143   __asm ("movw %w0, %%gs" :: "q" (val))
 144 # endif
 145
 146 #ifdef NEED_DL_SYSINFO
 147 # define INIT_SYSINFO \
 148   _head->sysinfo = GLRO(dl_sysinfo)
 149 # define SETUP_THREAD_SYSINFO(pd) \
 150   ((pd)->header.sysinfo = THREAD_GETMEM (THREAD_SELF, header.sysinfo))
 151 # define CHECK_THREAD_SYSINFO(pd) \
 152   assert ((pd)->header.sysinfo == THREAD_GETMEM (THREAD_SELF, header.sysinfo))
 153 #else
 154 # define INIT_SYSINFO
 155 #endif
 156
 157 #ifndef LOCK_PREFIX
 158 # ifdef UP
 159 #  define LOCK_PREFIX  /* nothing */
 160 # else
 161 #  define LOCK_PREFIX "lock;"
 162 # endif
 163 #endif
 164
 165 static inline void __attribute__ ((unused, always_inline))
 166 tls_fill_user_desc (union user_desc_init *desc,
 167                     unsigned int entry_number,
 168                     void *pd)
 169 {
 170   desc->vals[0] = entry_number;
 171   /* The 'base_addr' field.  Pointer to the TCB.  */
 172   desc->vals[1] = (unsigned long int) pd;
 173   /* The 'limit' field.  We use 4GB which is 0xfffff pages.  */
 174   desc->vals[2] = 0xfffff;
 175   /* Collapsed value of the bitfield:
 176      .seg_32bit = 1
 177      .contents = 0
 178      .read_exec_only = 0
 179      .limit_in_pages = 1
 180      .seg_not_present = 0
 181      .useable = 1 */
 182   desc->vals[3] = 0x51;
 183 }
 184
 185 /* Code to initially initialize the thread pointer.  This might need
 186    special attention since 'errno' is not yet available and if the
 187    operation can cause a failure 'errno' must not be touched.  */
 188 # define TLS_INIT_TP(thrdescr) \
 189   ({ void *_thrdescr = (thrdescr);                                            \
 190      tcbhead_t *_head = _thrdescr;                                            \
 191      union user_desc_init _segdescr;                                          \
 192      int _result;                                                             \
 193                                                                               \
 194      _head->tcb = _thrdescr;                                                  \
 195      /* For now the thread descriptor is at the same address.  */             \
 196      _head->self = _thrdescr;                                                 \
 197      /* New syscall handling support.  */                                     \
 198      INIT_SYSINFO;                                                            \
 199                                                                               \
 200      /* Let the kernel pick a value for the 'entry_number' field.  */         \
 201      tls_fill_user_desc (&_segdescr, -1, _thrdescr);                          \
 202                                                                               \
 203      /* Install the TLS.  */                                                  \
 204      INTERNAL_SYSCALL_DECL (err);                                             \
 205      _result = INTERNAL_SYSCALL (set_thread_area, err, 1, &_segdescr.desc);   \
 206                                                                               \
 207      if (_result == 0)                                                        \
 208        /* We know the index in the GDT, now load the segment register.        \
 209           The use of the GDT is described by the value 3 in the lower         \
 210           three bits of the segment descriptor value.                         \
 211                                                                               \
 212           Note that we have to do this even if the numeric value of           \
 213           the descriptor does not change.  Loading the segment register       \
 214           causes the segment information from the GDT to be loaded            \
 215           which is necessary since we have changed it.   */                   \
 216        TLS_SET_GS (_segdescr.desc.entry_number * 8 + 3);                      \
 217                                                                               \
 218      _result == 0 ? NULL                                                      \
 219      : "set_thread_area failed when setting up thread-local storage\n"; })
 220
 221 # define TLS_DEFINE_INIT_TP(tp, pd)                                           \
 222   union user_desc_init _segdescr;                                             \
 223   /* Find the 'entry_number' field that the kernel selected in TLS_INIT_TP.   \
 224      The first three bits of the segment register value select the GDT,       \
 225      ignore them.  We get the index from the value of the %gs register in     \
 226      the current thread.  */                                                  \
 227   tls_fill_user_desc (&_segdescr, TLS_GET_GS () >> 3, pd);                    \
 228   const struct user_desc *tp = &_segdescr.desc
 229
 230
 231 /* Return the address of the dtv for the current thread.  */
 232 # define THREAD_DTV() \
 233   ({ struct pthread *__pd;                                                    \
 234      THREAD_GETMEM (__pd, header.dtv); })
 235
 236
 237 /* Return the thread descriptor for the current thread.
 238
 239    The contained asm must *not* be marked volatile since otherwise
 240    assignments like
 241         pthread_descr self = thread_self();
 242    do not get optimized away.  */
 243 # define THREAD_SELF \
 244   ({ struct pthread *__self;                                                  \
 245      asm ("movl %%gs:%c1,%0" : "=r" (__self)                                  \
 246           : "i" (offsetof (struct pthread, header.self)));                    \
 247      __self;})
 248
 249 /* Magic for libthread_db to know how to do THREAD_SELF.  */
 250 # define DB_THREAD_SELF \
 251   REGISTER_THREAD_AREA (32, offsetof (struct user_regs_struct, xgs), 3) \
 252   REGISTER_THREAD_AREA (64, 26 * 8, 3) /* x86-64's user_regs_struct->gs */
 253
 254
 255 /* Read member of the thread descriptor directly.  */
 256 # define THREAD_GETMEM(descr, member) \
 257   ({ __typeof (descr->member) __value;                                        \
 258      if (sizeof (__value) == 1)                                               \
 259        asm volatile ("movb %%gs:%P2,%b0"                                      \
 260                      : "=q" (__value)                                         \
 261                      : "0" (0), "i" (offsetof (struct pthread, member)));     \
 262      else if (sizeof (__value) == 4)                                          \
 263        asm volatile ("movl %%gs:%P1,%0"                                       \
 264                      : "=r" (__value)                                         \
 265                      : "i" (offsetof (struct pthread, member)));              \
 266      else                                                                     \
 267        {                                                                      \
 268          if (sizeof (__value) != 8)                                           \
 269            /* There should not be any value with a size other than 1,         \
 270               4 or 8.  */                                                     \
 271            abort ();                                                          \
 272                                                                               \
 273          asm volatile ("movl %%gs:%P1,%%eax\n\t"                              \
 274                        "movl %%gs:%P2,%%edx"                                  \
 275                        : "=A" (__value)                                       \
 276                        : "i" (offsetof (struct pthread, member)),             \
 277                          "i" (offsetof (struct pthread, member) + 4));        \
 278        }                                                                      \
 279      __value; })
 280
 281
 282 /* Same as THREAD_GETMEM, but the member offset can be non-constant.  */
 283 # define THREAD_GETMEM_NC(descr, member, idx) \
 284   ({ __typeof (descr->member[0]) __value;                                     \
 285      if (sizeof (__value) == 1)                                               \
 286        asm volatile ("movb %%gs:%P2(%3),%b0"                                  \
 287                      : "=q" (__value)                                         \
 288                      : "0" (0), "i" (offsetof (struct pthread, member[0])),   \
 289                      "r" (idx));                                              \
 290      else if (sizeof (__value) == 4)                                          \
 291        asm volatile ("movl %%gs:%P1(,%2,4),%0"                                \
 292                      : "=r" (__value)                                         \
 293                      : "i" (offsetof (struct pthread, member[0])),            \
 294                        "r" (idx));                                            \
 295      else                                                                     \
 296        {                                                                      \
 297          if (sizeof (__value) != 8)                                           \
 298            /* There should not be any value with a size other than 1,         \
 299               4 or 8.  */                                                     \
 300            abort ();                                                          \
 301                                                                               \
 302          asm volatile  ("movl %%gs:%P1(,%2,8),%%eax\n\t"                      \
 303                         "movl %%gs:4+%P1(,%2,8),%%edx"                        \
 304                         : "=&A" (__value)                                     \
 305                         : "i" (offsetof (struct pthread, member[0])),         \
 306                           "r" (idx));                                         \
 307        }                                                                      \
 308      __value; })
 309
 310
 311
 312 /* Set member of the thread descriptor directly.  */
 313 # define THREAD_SETMEM(descr, member, value) \
 314   ({ if (sizeof (descr->member) == 1)                                         \
 315        asm volatile ("movb %b0,%%gs:%P1" :                                    \
 316                      : "iq" (value),                                          \
 317                        "i" (offsetof (struct pthread, member)));              \
 318      else if (sizeof (descr->member) == 4)                                    \
 319        asm volatile ("movl %0,%%gs:%P1" :                                     \
 320                      : "ir" (value),                                          \
 321                        "i" (offsetof (struct pthread, member)));              \
 322      else                                                                     \
 323        {                                                                      \
 324          if (sizeof (descr->member) != 8)                                     \
 325            /* There should not be any value with a size other than 1,         \
 326               4 or 8.  */                                                     \
 327            abort ();                                                          \
 328                                                                               \
 329          asm volatile ("movl %%eax,%%gs:%P1\n\t"                              \
 330                        "movl %%edx,%%gs:%P2" :                                \
 331                        : "A" ((uint64_t) cast_to_integer (value)),            \
 332                          "i" (offsetof (struct pthread, member)),             \
 333                          "i" (offsetof (struct pthread, member) + 4));        \
 334        }})
 335
 336
 337 /* Same as THREAD_SETMEM, but the member offset can be non-constant.  */
 338 # define THREAD_SETMEM_NC(descr, member, idx, value) \
 339   ({ if (sizeof (descr->member[0]) == 1)                                      \
 340        asm volatile ("movb %b0,%%gs:%P1(%2)" :                                \
 341                      : "iq" (value),                                          \
 342                        "i" (offsetof (struct pthread, member)),               \
 343                        "r" (idx));                                            \
 344      else if (sizeof (descr->member[0]) == 4)                                 \
 345        asm volatile ("movl %0,%%gs:%P1(,%2,4)" :                              \
 346                      : "ir" (value),                                          \
 347                        "i" (offsetof (struct pthread, member)),               \
 348                        "r" (idx));                                            \
 349      else                                                                     \
 350        {                                                                      \
 351          if (sizeof (descr->member[0]) != 8)                                  \
 352            /* There should not be any value with a size other than 1,         \
 353               4 or 8.  */                                                     \
 354            abort ();                                                          \
 355                                                                               \
 356          asm volatile ("movl %%eax,%%gs:%P1(,%2,8)\n\t"                       \
 357                        "movl %%edx,%%gs:4+%P1(,%2,8)" :                       \
 358                        : "A" ((uint64_t) cast_to_integer (value)),            \
 359                          "i" (offsetof (struct pthread, member)),             \
 360                          "r" (idx));                                          \
 361        }})
 362
 363
 364 /* Atomic compare and exchange on TLS, returning old value.  */
 365 #define THREAD_ATOMIC_CMPXCHG_VAL(descr, member, newval, oldval) \
 366   ({ __typeof (descr->member) __ret;                                          \
 367      __typeof (oldval) __old = (oldval);                                      \
 368      if (sizeof (descr->member) == 4)                                         \
 369        asm volatile (LOCK_PREFIX "cmpxchgl %2, %%gs:%P3"                      \
 370                      : "=a" (__ret)                                           \
 371                      : "0" (__old), "r" (newval),                             \
 372                        "i" (offsetof (struct pthread, member)));              \
 373      else                                                                     \
 374        /* Not necessary for other sizes in the moment.  */                    \
 375        abort ();                                                              \
 376      __ret; })
 377
 378
 379 /* Atomic logical and.  */
 380 #define THREAD_ATOMIC_AND(descr, member, val) \
 381   (void) ({ if (sizeof ((descr)->member) == 4)                                \
 382               asm volatile (LOCK_PREFIX "andl %1, %%gs:%P0"                   \
 383                             :: "i" (offsetof (struct pthread, member)),       \
 384                                "ir" (val));                                   \
 385             else                                                              \
 386               /* Not necessary for other sizes in the moment.  */             \
 387               abort (); })
 388
 389
 390 /* Atomic set bit.  */
 391 #define THREAD_ATOMIC_BIT_SET(descr, member, bit) \
 392   (void) ({ if (sizeof ((descr)->member) == 4)                                \
 393               asm volatile (LOCK_PREFIX "orl %1, %%gs:%P0"                    \
 394                             :: "i" (offsetof (struct pthread, member)),       \
 395                                "ir" (1 << (bit)));                            \
 396             else                                                              \
 397               /* Not necessary for other sizes in the moment.  */             \
 398               abort (); })
 399
 400
 401 /* Set the stack guard field in TCB head.  */
 402 #define THREAD_SET_STACK_GUARD(value) \
 403   THREAD_SETMEM (THREAD_SELF, header.stack_guard, value)
 404 #define THREAD_COPY_STACK_GUARD(descr) \
 405   ((descr)->header.stack_guard                                                \
 406    = THREAD_GETMEM (THREAD_SELF, header.stack_guard))
 407
 408
 409 /* Set the pointer guard field in the TCB head.  */
 410 #define THREAD_SET_POINTER_GUARD(value) \
 411   THREAD_SETMEM (THREAD_SELF, header.pointer_guard, value)
 412 #define THREAD_COPY_POINTER_GUARD(descr) \
 413   ((descr)->header.pointer_guard                                              \
 414    = THREAD_GETMEM (THREAD_SELF, header.pointer_guard))
 415
 416
 417 /* Get and set the global scope generation counter in the TCB head.  */
 418 #define THREAD_GSCOPE_IN_TCB      1
 419 #define THREAD_GSCOPE_FLAG_UNUSED 0
 420 #define THREAD_GSCOPE_FLAG_USED   1
 421 #define THREAD_GSCOPE_FLAG_WAIT   2
 422 #define THREAD_GSCOPE_RESET_FLAG() \
 423   do                                                                          \
 424     { int __res;                                                              \
 425       asm volatile ("xchgl %0, %%gs:%P1"                                      \
 426                     : "=r" (__res)                                            \
 427                     : "i" (offsetof (struct pthread, header.gscope_flag)),    \
 428                       "0" (THREAD_GSCOPE_FLAG_UNUSED));                       \
 429       if (__res == THREAD_GSCOPE_FLAG_WAIT)                                   \
 430         lll_futex_wake (&THREAD_SELF->header.gscope_flag, 1, LLL_PRIVATE);    \
 431     }                                                                         \
 432   while (0)
 433 #define THREAD_GSCOPE_SET_FLAG() \
 434   THREAD_SETMEM (THREAD_SELF, header.gscope_flag, THREAD_GSCOPE_FLAG_USED)
 435 #define THREAD_GSCOPE_WAIT() \
 436   GL(dl_wait_lookup_done) ()
 437
 438 #endif /* __ASSEMBLER__ */
 439
 440 #endif  /* tls.h */